Electric power converters are devices that enable the conversion of electric energy between AC (alternating current) and DC (direct current) and/or from one voltage level to another and/or from one frequency to another, for example. Examples of such electric power converters include a rectifier, an inverter and a frequency converter, for example.
As an example, an inverter is an electrical device enabling conversion of DC power from a DC power source to AC power. The term ‘inverter’ generally refers to an electronic device or circuitry that is able to convert direct current to alternating current. An example of the inverter is a semiconductor bridge implemented by means of controllable semiconductor switches, such as IGBTs (Insulated-gate Bi-polar Transistor) or FETs (Field-Effect Transistor), which are controlled according to a modulation or control scheme used.
One example of an electric system comprising one or more inverters is a photovoltaic system, such as a photovoltaic power plant or generator, in which one or more photovoltaic panels supply DC power to the inverter which converts the DC power to AC power, which may further be supplied to various AC loads via an AC network, for example. Large photovoltaic power plants may comprise a plurality of parallel inverters each receiving DC power from an array of photovoltaic panels.
Often power plants, such as photovoltaic power plants, or other systems utilizing inverters or other electric power converters, may comprise converters which are made-to-order manufactured or mass manufactured. As a result, they may be intentionally made very similar to each other and possibly only occasionally some special modifications or alterations are done for individual converters.
A problem related to such a system is that the system as a whole may not be sufficiently optimized and comprises a group of merely sub-optimized electric power converters. Moreover, such a system may not able to properly or adequately adapt to new situations or circumstances affecting the system.